Photographic emulsion



Jan. 2, 1940.

R. STEVENS PHoToGRAPHIc EMULsIoN yFiled Aug. 9, 19:58

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Jan. 2, 1940. R. STEVENS 2,185,798 PHO'I/'OGRAPHIC EMULSION V Filed Aug. 9|, 1938 2 Sheets-Sheet 2 fla. 13.

7i 76 Pa dv sy f A rrys Patented Jan. 2, 1940 2,185,798 PHOTOGRAPHIC EMULsIoN Ren Stevens, Antwerp, Belgium Application August 9, 1938, Serial No. 223,873 In Austria May 9, 1935 5 Claims.

The present application is a continuation in part of my applications for U. S. Letters Patent Serial No. 78,408, filed May 7, 1936, and Serial No. 125,039, led February 10, 1937.

A My invention relates to photographic materials and more especially to silver halide emulsions which are sensitized with a new kind of polymethenyl dyestuis.

In a prior application for U. S. Letters Patent l Serial No. 63,737, iiled February 13, 1936, I have disclosed as sensitizers for photographic silver halide emulsions dyestuffs which contain at least one thiodiazole ring in which the two nitrogen atoms are in meta positions with respect to the sulfur atom, or to the oxygen or selenium atom, by which the sulfur atom may be replaced accordlng to the formula 30 compounds provided that they thiodiazoline nucleus is substituted according to the formula R-N N 3 4 R"-o2 sc-CILv 35 \1/ wherein R is an aryl radical and more especially phenyl or alpha mono-halogen-substituted phenyl or alpha naphthyl or beta naphthyl, while R is H or an alkyl and R" is an alkyl. Thus, according to my invention polymethenyl dyestuis can be produced from 3-aryl-2-monoor dialkyl- 2:3-dihydrothiodiazoles(123:4), which in the 5- position carry a reactive group such asy the methyl group.

The manufacture of these dhydrothiazole or thiodiazoline compounds has been partly described by Wuyts and Lacourt in Bulletin de la Classe des Sciences de IAcadmie Royale de Belgique-5e Srie, XIX, 1933-page 543. Thiodiazolines with a methyl group in the 5-position and which are substituted in the manner required according to 'my invention may for instance be obtained by condensation of alphaphenyl, beta-thioacetyl-hydrozine with an aldehyde or a ketone. The phenyl group of this hydrazine compound may be substituted by a halogen atom or may be replaced by naphthyl forzthe production of the correspondingly substituted thiodiazolines. All these hydrazine compounds can easily be produced from phenylhydrazine or mono-halogen-phenylhydrazine or naphthylhydrazine by acting thereon with acetic anhydrid and treating the product thus obtained with P2S5.

For the production of my new dyestuffs I convert these substituted thiodiazoline bases in any convenient manner, for instance by means of an appropriate ester such as dimethyl sulfate or cthyliodide or methyliodide, into the corresponding alkyl Quaternary ammonium salts. The quaternary salts thus obtained are treated in the presence of a solvent and o-f a cyanine-condensing agent, whereby polymethenyl dyestuffs are formed. While substances such as pyridine may be used as solvents, I found that the best yields are obtained with acetic anhydrid as solvent.

'Ihe condensing agent serves vfor introducing the methenyl chain into the dyestui to be produced. Therefore the substances known to effect condensation in the production of other kinds of cyanine or carbocyanine dyestuis may be employed in the condensation according to my invention. Such condensing agents are for instance alkyl esters of ortho acids, such as ortho formic or acetic or propionic acid, diphenylformamidine, diphenylacetamidine, beta-ethoxyacroleinacetal, glutaconealdehyde-dianilide-hydrochloride and bcta-anilino-acrolein-anil.

In the manner described above symmetrical dyestuis are obtained of the general formula wherein the R are similar or dissimilar phenyl or alpha or vbeta naphthyl or mono-halogen-substituted phenyl radicals, while the R are H or similar or dissimilar alk'yl radicals, the R" and X being similar or dissimilar alkyl radicals, while Y is an inorganic anion, for instance Cl-, Br, I, C104, CH3SO4 01 CH3.CsH4.HSO4-.

adding to the mixture of substances to be conl densed, as described above,. another heterocyclic nitrogen compound and more particularly a n is an integer and may for instance be 0, 1, 2 or 3,

substance selected from the group constituted by the pyridines, quinolines, quinaldines, thiazoles, thiazolines, indolenins, pyrimidines, quinazolines, thiodiazoles, furodiazoles, selenodiazoles, methyland ethyl-diazoles, methyland ethylfurodiazoles, methyland ethyl-selenodiazoles.

In this manner I obtain dyestuffs of the following general formula wherein R is againphenyl or mono-halogen-substituted phenyl or naphthyl, R is H or alkyl, while R", X and X' are similar or dissimilar alkyls, n is an integer, which may again be 0 or possess a high value such as 6, and Z represents the nonmetallic atoms of a heterocyclic nucleus constituted by lve or six members, which nucleus may carry substituents and may form part of a condensed system of nuclei.

Styryl compounds can be obtained on principle in the same manner by employing an appropriate condensing agent, for instance paradimethyl aminobenzaldehyde.

It is an advantage of my invention that a great number of more or less different dyestuffs with more or less different sensitizing capacity and solubility properties can be obtained according to a single method of synthesis by simply varying the aldehyde or ketone with which the aryl hydrazine is condensed in the manner mentioned above. Other dyestuifs of the same class can be obtained by employing different aryl hydrazines as has been described above, .or by the use of different esters for the conversion of the substituted thiodiazoline bases into the alkyl quaternary salts. In every case however it is of decisive importance that the nitrogen atom which is not linked with that carbon atom which carries the reactive methyl group, is substituted by an laryl radical-and that that carbon atom, which is linked to the aryl-substituted nitrogen atom, carries at least one alkyl group. These substitutions are surprisingly the conditions which allow the condensation into polymethenyl compounds. All the variations mentioned can be effected in practice in a very simple manner and very quickly, since neither the production of the corresponding hydrazine compounds nor their conversion into the'thiodiazoline bases oer great difficulties.

The dyestuifs to be obtained according to my invention can b e incorporated in the silver halide emulsion to be sensitized, before, during or after manufacture, or the,emulsion layers may be bathed in a solution of the-dyestuif.

The invention may be illustrated more in detail by the following examples which show the production of the sensitizing dyestuifs:

Example 1 2o grams 2:5-d1methy1-3-pheny1-2:za-dihydrothiodiazole (1:3:4) methiodide, obtained by condenslng in a sealed tube equi-molecular quantities of 2 5dimethyl3phenyl2`z B-dihydrothiodiazole (1:3:4) and methyl iodide in a boiling water bath for 24 hours, are dissolved in 200 ccms. acetic anhydrid;20 ccms. triethyl orthoformate are added and the whole is boiled for 20 minutes in a reux apparatus. After cooling, the dyestul is precipitated by the addition of ether, washed with water and recrystallized from alcohol. The dyestuil has probably the following composition:

and sensitizes a gelatine silver halide emulsion up to about 620 ,un with a miximum at 560 mi.

Example 2 8.4 grams of the quaternary salt used in Example 1 is dissolved in 36 ccms. absolute alcohol with 4.2 grams paradimethylaminobenzaldehyde. To the boiling solution are added 3 ccms. pperidine and boiling is continued for 5 minutes. The red dye which is formed immediately, is precipitated, after cooling, with ether, washed with water and recrystallized from a mixture of alcohol and ether. It has most probably the following structure:

and sensitizes a photographic emulsion up to about 640ML with a broad maximum extending from 560 to 580m.

Example 3 It sensitizes a photographic gelatine silver halide emulsion between 600 and 740ML with a maximum at 720ML.'

' Example 4 7 grams of the quaternary salt of Example 1 are boiled together with 7 ccms. triethyl ortho-acetate in 30 ccms. acetic anhydrid for of an hour. The so-formed dyestui is precipitated with ether, washed with water and recrystallized from a mixture of methyl alcohol and ether. It has most probably the following structure:

'I'he sensitizing action of this dyestuff in a gelatino-silverl halide emulsion extends to about 580ML with a maximum at 550ML.

l dihydrothiodiazole (1:3:4) are treated with 3 .8

Example 5 'l grams of the condensation product obtained by heating equmolecular quantities of 2:2'25-tr1- methyl-3-phenyl-2 B-dihydrothiodiazole (1 3 :4) with methyl iodide in a sealed tube in a boiling water bath for 36 hours, are dissolved in 30 ccms. acetic anhydrid and after addition of 4ccms. triethyl ortho-formate boiling is continued for 1 hour. The so-formed dyestuff is precipitated with ether, washed with water and recrystallized from methyl alcohol. It has most probably the following structure:

y and sensitizes a gelatine silver halide emulsion up to 600W. `with a maximum approximately at 550ML.

Example 6 7.9 grams 2 5-dimethyl-3-phenyl-2 z 3dihydro thiodiazole (1:3:4) ethiodide are melted with 4.7 grams diphenyl-formamidine at a temperature of 115 C. for about one hour. The product thus i, obtained has most probably the following structure:

oms-N--N i IV H i and is useful as an intermediate product for the manufacture of symmetrical and asymmetrical carbocyanines by condensation with various heterocyclic Quaternary ammonium salts. A sym- By boiling together for 10 minutes a mixture of 3 grams of the above-mentioned intermediate product with 1.9 grams a-naphthylquinoline ethiodide in the presence of ccms. acetic anhydrid, a red dyestuff is formed, havingmost probably the following composition:

Ca \S/ U The dyestuif is precipitated with ether, washed with water and recrystallized from a mixture of methyl alcohol and ether. When incorporated in a photographic emulsion, it extends the sensivity to the longer wave lengths with a maximum near 550ML.l y

Example 7 y 10 grams 2 5-dimethyl-3-beta-naphthyl-2 3- ccms. ethyliodide on the boiling water bath during 14 hours to be converted into the corresponding alkyl quaternary salt. The solid mass v thus formed is washed first with a small quantity of ethyl ether and subsequently with acetone. 5 grams of the quaternary salt thus obtained are boiled with ccms. acetic anhydrid and 5.5 ccms. orthoethylformate during 3 hours. A precipitate is produced by -an addition of ether and is thoroughly washed first with ether, subsequently with water and finally with a small quantity of acetone. The product obtained is extracted by means of methyl alcohol and from the solution thus obtained the pure dyestu' is precipitated by an addition of ether. This dyestuff has probably the following formula:

and sensitizes a silver halide emulsion up to about 640ML with a maximum at 560ML.

Example 8 2.1 grams of 2:5-dimethy1f3-beta-naphthyl- 1-2:3dihydrothiodiazole (1:3:4) ethiodide are i It sensitizes a saver hande 'mu1sion up to about '740ML with a maximum at '720p/l.

Erample 9 l1o grams 2:5-dimethyi zi-alpha-napmnyl-2;3- dihydrothiodiazole (1:3:4) are heated with 3.8

ccms. ethyliodide on the boiling water bath during 14 hours. The solid product thus obtained is Washed first with a small quantity of ether'and subsequently with acetone. 5 grams of. the quaternary salt thus obtained are mixed with 50 ccms. acetic anhydrid and 5.5 ccms. ortho-ethyl-formate and the mixture is boiled during 3 hours. A precipitate is produced by the addition of ether and is thoroughly washed first with ether, subsequently with water and finally with a small quantity of acetone. The washed product is extracted with methyl alcohol and from thersolution thus obtained the pure dyestuff is precipi- 3 ccms. triethylamine are i' phenyl-thiodiazolines.

tated by an addition of ether. probably the following formula:

@I il? II H Example 2.1 grams 2:5-dimethyl-3-a1pha-naphthyl-2:3- dihydrothiodiazole (1:3:4)ethiodide are mixed `with 0.6 grams alpha-aniline-acrolein-anil-hydrochloride and with 3.5 ccms. acetic anhydrid. 3 ccms. triethylamine areadded to the mixture and the whole is moderately heated on the water bath until it has assumed a beautiful blue color. Ether is now added to produce a precipitate which is washed with water and thereupon extracted with alcohol. 'I'he dyestui is obtained from the .solution thus produced by an addition of ether It probably possesses the following formula:

It sensitizes a silver halide emulsion up to about 700ml with a maximum at 650ML.

Naphthyl-thiodiazolines such as are used as starting materials in Examples 7 to 10, can be obtained in a similar manner as the corresponding In order to prepare the alpha-naphthyl compounds, one may start from alpha-naphthyl-hydrazines, which are treated according to the method of Freund-Schuftan (Berichte der Deutschen Chemischen Geselll CzHi-N- N schaft, vol. 24, page 4183) with an excess of acetic anhydrid, yielding needles of Nacetyl-N alpha-naphthyl-hydrazine with a melting point of 142-143 C. This compound is thereafter boiled during half an hour with P285 in benzene,

' whereby N'-thioacetyl-N-alpha-naphthyl-hydrazine is formed which can be extracted from the benzene solution by means of NaOH and can be precipitated from the solution thus obtained with HC1. The thio-compound, when re-crystallized from Water, melts at 120 C. Condensation of the thio-compound with aldeh'ydes or ketones results in the formation of the corresponding alphanaphthyl-thiodiazolines.

N -thio-acetyl -N- alpha naphthyl hydrazine may for instance be condensed with acetic aldehyde according to the method of Wuyts, whereby 2 :5-dimethyl-3-alpha-naphthy1-2 3-dihydrothiodiazole (1:3:4), melting at 61 C., is obtained. Condensation with acetone results in the formation of 2 :2' :5-trimethyl-3-alpha-naphthyl-2 3- dihydrothiodiazole (1:314) melting at 125 C. Condensation with formaldehyde results in the formation of an oil composed of 5-methyl3 alpha naphthyl-2:S-dihydrothiodiazole (l :3:41)

The beta-naphthyl compounds, for instance The dyestufr has 2:5-dimethy1-3-beta naphthyl-z-dihydrothio diazole (1:3:4), melting at 12S-126 C., or 5- methyl-3- beta naphthyl-Z: B-dihydrothiodiazole (1:324), melting at 13S-135 C., can be synthesized in an analogous manner.

Example 11 3 grams 2:5-dimethyl-3-phenyl-2:I3-dihydrothiodiazole (1:3:4)ethiodide and 1.2 grams glutacone-dialdehyde-dianilhydrochloride and 2 ccms. triethylamine are boiled minutes in 15 ccms. alcohol. While the solution is allowed to cool, a blue dyestuff crystallizesout, which is Washed with water and re-crystallized from alcohol. 'I'his dyestui is a symmetrical heptacarbocyam'ne with 11:3. It sensitizes a silver bromide gelatine emulsion from 660ML to 820/1 with a maximum at about 780ML.

Eampl e 12 Equimolecular quantities of ethyliodide and 2:5 dimethyl- 3 -phenyl- 2:3 -dihydrothiodiazole (1:3 :4) are heated in a boiling water bath during 36 hours; 4.5 grams of the quatenary salt thus obtained are condensed with an equimolecular quantity, amounting to 2.7 grams, of diphenylformamidine by heating the mixture minutes in an oil bath to 120 C. The condensation product is washed with water and re-crystallized from alcohol. Equimolecular quantities, viz. 1 gram of the condensation product and 0.7 gram -benzoxazole-benzylbromide are boiled in 5 ccms.

pyridine during 20 minutes. The dyestuif thus formed is precipitated with ether, washed with water and re-crystallized from alcohol. It has most probably the following structure:

The alcoholic solution of this dyestuf absorbs up to about 590/11. `The dyestuff sensitizes a silver halide emulsion up to about 620ML with a maximum at 560ml.

Eample 13 2:5 -dimethyl- 3 -alpha-naphthyl-2:3-dihydrothiodiazole (1:3:4) -ethiodide is condensed With benzoxazole-benzylbromide in the same manner as described with reference to Example 12. The product is an asymmetrical carbocyanine dyestui which absorbs up to about 538ml, while sensitizing up to about 565m). with a maximum at 530,u,a.

Example 14 600ML with a maximum at 560ML, can be obtained from 2:5-dimethyl- 3 -beta-naphthyl- 2:3 -dihydrothiodiazole (1:3:4) -ethiodide and benzoxazole-benzylbromide in the manner described with reference to Example 12.

Example 15 2.4 grams 2:5-dimethyl-3-alpha-naphthyl and l2:S-dihydrothiodiazole `(123:4) are heated in a aisance temperature of 50"A C.' is maintained during 2 hours, whereupon a dyestuff compoundl can be precipitated with ether. 'I'his compound is thereafter dissolved in alcohol and the ethiodide of the dyestu is precipitated from the alcoholic solution by means of a saturated solution of potassium iodide. The dyestui! is washed with water and re-crystallized from alcohol. Most probably it has the following structure:

Figs. 2-15 are corresponding curves of an emulsion of the same kind, but sensitized by an addition of the dyestuifs of the above Examples 1 to 14, respectively, while Fig. 16 is the corresponding curve of a nonsensitized silver-chloride emulsion and Fig. 17 the curve of the same emulsion sensitized with the dyestu of Example 15.

'I'he correctness of the formulae, used in this specication and the claims alxed to it, for dening the new substances depends on the correctness of the assumptions nowadays adopted by the experts in the held of cyanine and related dyestuifs. Therefore although these formulae may be subject to corrections or changes in correspondence with the scientic development of chemistry, they clearly designate to the expert, who knows the present state of the art, the nature of the substances thus dened.

Various changes may be made in the details disclosed in the foregoing specication without departing from the invention or sacrificing the advantages thereof.K

I claim:

1. As a photographic material. a silver halide emulsion'with an addition of a dyestuil of the general formula.l

w1 if 2 1 /5 GH=(CH--GH=)., RII/ wherein R is a`member of the group constituted by phenyl, the naphthyls and the mono-halogensubstituted phenyls, while R' is a member of the group constituted by H and the alkyls, R", X and X are alkyls, Y is an anion and Z represents the non-metallic atoms necessary to complete a het` erocyclio nucleus selected from the group consisting of veand six-membered heterocyclic nuclei;l n being a member of the group constituted by the integers including 0.

2. As a photographic material, a silver halide emulsion with an addition of a dyestufl as dened -in claim -1, wherein the nucleus, which is completed by the atoms represented by Z, forms part of a condensed system of nuclei.

3. As a photographic material, a silver halideemulsion with an addition of a dyestuff general formula of the RII n' s s a' wherein the R are members of the group constituted by phenyl, the naphthyls and the monohalogen-substituted phenyls, while the R' are members of the group constituted by H and the alkyls, R", X and X' are alkyls and Y is an inorganic anion; n being a member of the group constituted by the integers including 0.

4. As a photographic material, a silver halide emulsion with an addition of a dyestuif as defined in claim 1, wherein the polymethenyl chain carries a substituent.

5. As a photographic material, a silver halide emulsion with an addition of -a dyestuff as deilned in claim 3. wherein the polymethenyl chain carries a substituent.

mi: s'ravmNs. 

